Repairing of hairline cracks in plaster
RELATED MATERIALS
- UNICRET cement-lime mortar
- UNICRET-FAST fast-setting mortar
- PLANFIX polymer-modified cement putty
- PLANFIX-FINE extra-fine cement putty
- ADIPLAST polymer latex additive
- ISOMASTIC-A elastoplastic acrylic sealant
I. NATURE OF THE PROBLEM – REQUIREMENTS
Hairline cracks often appear on plaster due to shrinkage, thermal expansion and contraction or minor structural movements. Although they are not a serious structural defect, these cracks allow moisture to penetrate and gradually deteriorate the render or finish.
II. SOLUTION
Hairline cracks should be sealed with an elastoplastic sealant or filled with a polymer-modified cement mortar and then finished with a putty. Materials must have good adhesion, flexibility and water resistance.
III. APPLICATION
- Crack preparation: Enlarge the cracks to a V-shaped groove about 3–5 mm wide. Remove loose particles and dust using a wire brush and compressed air. Wet the surfaces before filling.
- Filling with sealant: For fine cracks, press ISOMASTIC-A elastoplastic acrylic sealant into the groove using a caulking gun. Smooth the surface with a trowel or spatula. After the sealant cures, prime the area if necessary and finish with a suitable paint.
- Filling with mortar: For larger cracks requiring mortar, prepare a mixture of UNICRET or UNICRET-FAST with ADIPLAST (ratio of ADIPLAST : water = 1 : 3) to improve adhesion and elasticity. Fill the groove thoroughly and smooth with a trowel. If cracks are extensive, embed a strip of fiberglass mesh into the fresh mortar. After the mortar has set, apply a coat of PLANFIX or PLANFIX-FINE putty to achieve a smooth surface.
- Final finishing: After curing, lightly sand the surface if needed and repaint or render to match the surrounding area.
IV. REMARKS
- Work at ambient and substrate temperatures between +5°C and +35°C.
- Ensure the substrate is clean, sound and free of dust, oil and other contaminants.
- Do not retemper or add water to mortar that has begun to set.
- Protect repaired areas from direct sun, frost and strong wind until the material has cured.
- Wear protective gloves and goggles and follow the safety instructions of each material.
RELATED MATERIALS
- UNICRET cement-lime mortar
- UNICRET-FAST fast-setting mortar
- PLANFIX polymer-modified cement putty
- PLANFIX-FINE extra-fine cement putty
- ADIPLAST polymer latex additive
- ISOMASTIC-A elastoplastic acrylic sealant
I. NATURE OF THE PROBLEM – REQUIREMENTS
Hairline cracks often appear on plaster due to shrinkage, thermal expansion and contraction or minor structural movements. Although they are not a serious structural defect, these cracks allow moisture to penetrate and gradually deteriorate the render or finish.
II. SOLUTION
Hairline cracks should be sealed with an elastoplastic sealant or filled with a polymer-modified cement mortar and then finished with a putty. Materials must have good adhesion, flexibility and water resistance.
III. APPLICATION
- Crack preparation: Enlarge the cracks to a V-shaped groove about 3–5 mm wide. Remove loose particles and dust using a wire brush and compressed air. Wet the surfaces before filling.
- Filling with sealant: For fine cracks, press ISOMASTIC-A elastoplastic acrylic sealant into the groove using a caulking gun. Smooth the surface with a trowel or spatula. After the sealant cures, prime the area if necessary and finish with a suitable paint.
- Filling with mortar: For larger cracks requiring mortar, prepare a mixture of UNICRET or UNICRET-FAST with ADIPLAST (ratio of ADIPLAST : water = 1 : 3) to improve adhesion and elasticity. Fill the groove thoroughly and smooth with a trowel. If cracks are extensive, embed a strip of fiberglass mesh into the fresh mortar. After the mortar has set, apply a coat of PLANFIX or PLANFIX-FINE putty to achieve a smooth surface.
- Final finishing: After curing, lightly sand the surface if needed and repaint or render to match the surrounding area.
IV. REMARKS
- Work at ambient and substrate temperatures between +5°C and +35°C.
- Ensure the substrate is clean, sound and free of dust, oil and other contaminants.
- Do not retemper or add water to mortar that has begun to set.
- Protect repaired areas from direct sun, frost and strong wind until the material has cured.
- Wear protective gloves and goggles and follow the safety instructions of each material.
